[C:1](#[N:3])[CH3:2].C([Li])CCC.[Br:9][C:10]1[CH:15]=[C:14]([O:16][CH3:17])[C:13]([O:18][CH3:19])=[CH:12][C:11]=1[CH2:20]Br.O>C1COCC1>[Br:9][C:10]1[CH:15]=[C:14]([O:16][CH3:17])[C:13]([O:18][CH3:19])=[CH:12][C:11]=1[CH2:20][CH2:2][C:1]#[N:3]To a solution of 0.3 mL of acetonitrile (5.8 mmoles, 1.8 eq.) in 15 mL of THF there are added, at −60° C., 1.77 mL of n-butyllithium (2M in cyclohexane, 3.5 mmoles, 1.1 eq.). The solution is stirred for 15 minutes at −60° C. and then 1 g of 1-bromo-2-(bromomethyl)-4,5-dimethoxybenzene (3.2 mmoles) dissolved in 5 mL of THF is added. The reaction mixture is stirred for 1 hour and then hydrolysed using 10 mL of water and extracted twice with ethyl acetate. The organic phases are combined and evaporated under reduced pressure. The crude reaction product is purified by chromatography on silica gel (eluant: methylcyclohexane/ethyl acetate (70/30)). After evaporating off the solvent under reduced pressure, 505 mg of an orange oil which crystallises in the form of a beige solid are obtained.
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